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Silicon Carbide or Aluminiun Oxide??

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Hi again everyone.


I am not in a position to import natural stones into South Africa right now. Furtunately there are a selection of synthetic stones available, relatively cheap.


Unfortunately the catalogue I have puts everything under the heading "Oil Stones" so I am not sure if I can use them with water. There are two types of stone available, Silicon Carbide and Aluminium Oxide. Does anybody have any information on these for me? Can I use either of them with water? I used another silicon Carbide Stone for a while with oil, but it made a terrible mess and I would rather stay with water.


The "Grit" values are also abscent and they merely specify "Course, medium and Fine." I am pretty sure the supplier will help me with that though.


I am planning on making my first beveled blades really soon and I would like to use the stones on them.

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Silicon carbide is a harder abrasive, but aluminum oxide is plenty hard for steel. Either will work. The biggest differences in stones are how they cut, which is a funtion of the abrasive and the binder used to "glue" the abrasive particles together. There is no way to know until you try them, sadly. Good luck.

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Thanks Howard


The catalogue I have says that the silicon carbide has a "Agressive cutting action" and is better suited to hardened steels. The Aluminium Oxide seems to be better for polishing and sharpening.


They are really cheap ($3.00)so I am going to get a selection and give them all a bash then.


Thanks again


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Sounds like a plan, Wayne. Just remember once you put oil on a stone, you can't use water with it. Admittedly my experience is limited but I'm not all that thrilled with water stones. I have a couple and I'll probably save them for sharpening tools but I have found the oil polishing stones to be better.


Doug Lester

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My experience is that Silicon Carbide oil stones are wonderful for removing large amounts of metal quickly. Aluminum Oxide is a little less aggressive. I do not know what sort of stones are available in South Africa, but do some research on tool and die polishing stones. There are an amazing variety of grits and binders available.


I have used both oil and water on the die stones. They are a great example of what happens when you use water on a stone that is designed for oil. Water causes the binder to break down faster, creating more slurry. For me, this is a positive development. In a machine shop, it might not be.


Best wishes,


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My experience is based mostly on norton stones and common vitrified siC and Al oxide die making stones.

Which is better depend from what you want.

If the stones are prefilled with oil, you can't have great result with water anyway; I suggest you to use white petroleum or kerosene. Talking about norton stones, krystolon SiC stone is very aggressive, has faster breakdown and leave a uniform matt finish comparable to a water stone. These are very good for shaping or removing a lot of metal.

India, Al oxide stone, has an harder binder, slower breakdown, and is better for sharpening and for shaping smaller pointy cutting tools. It leaves a brighter scratched finish.

Not prefilled die makers SiC stone often are made of green SiC carbide and when they are made to abrade softer metals they have a pretty hard bond, that make them work bad on steel, expecially larger grit.Al Oxide stone are made just for steel and usually cut better.

It's difficult to talk about all stones, because the bond makes a lot of difference. My favourite combo is probably SiC in soft bond.

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